A216192 a(n) = Smallest m >= 5 containing no twos when represented in any base from 3 through n.

9, 12, 28, 28, 28, 28, 28, 31

Offset: 3

Author

Nathan Fox, Mar 12 2013

Keywords

• nonn
• hard
• more
• base

Comments

If a(11) exists, it contains over 3000 digits.

No more terms < 10^154400. Most likely there are no more terms. - Chai Wah Wu, Mar 17 2016

Examples

			In base 3, 5=12, 6=20, 7=21, 8=22, 9=100.  The first representation containing no twos is that of 9, so a(3)=9.
		

Links

• Nathan Fox, Maple Program to compute a(n)

Crossrefs

Cf. A216194, A270037, A270038, A270039, A270040, A270041, A270042, A270043, A270044, A270045.

Programs

Mathematica

Table[SelectFirst[Range[5, 10^3], Total@ Map[Function[k, DigitCount[#, k, 2]], Range[3, n]] == 0 &], {n, 3, 20}] /. n_ /; MissingQ@ n -> Nothing (* Michael De Vlieger, Mar 09 2016, Version 10.2 *)